dart:io | Add Directory.CreateSystemTemp(template) and change Directory.CreateTemp(template).

runtime/bin/directory_android.cc

Index: runtime/bin/directory_android.cc
diff --git a/runtime/bin/directory_android.cc b/runtime/bin/directory_android.cc
index b48474d16c182afd02c165420c380c930d32c5be..6a2646a06ce01d6f9cee9444406f005265b643e3 100644
--- a/runtime/bin/directory_android.cc
+++ b/runtime/bin/directory_android.cc
@@ -382,33 +382,34 @@ static char* MakeTempDirectory(char* path_template) {
 }
 
 
-char* Directory::CreateTemp(const char* const_template) {
+char* Directory::CreateTemp(const char* const_template, bool system) {
   // Returns a new, unused directory name, modifying the contents of
   // dir_template.  Creates the directory with the permissions specified
   // by the process umask.
   // The return value must be freed by the caller.
   PathBuffer path;
-  path.Add(const_template);
-  if (path.length() == 0) {
+  if (system) {
     // Android does not have a /tmp directory. A partial substitute,
     // suitable for bring-up work and tests, is to create a tmp
     // directory in /data/local/tmp.
     //
     // TODO(4413): In the long run, when running in an application we should
-    // probably use android.content.Context.getCacheDir().
+    // probably use the appropriate directory from the Android API,
+    // probably what File.createTempFile uses.
     #define ANDROID_TEMP_DIR "/data/local/tmp"
     struct stat st;
     if (stat(ANDROID_TEMP_DIR, &st) != 0) {
       mkdir(ANDROID_TEMP_DIR, 0777);
     }
-    path.Add(ANDROID_TEMP_DIR "/temp_dir1_");
-  } else if ((path.AsString())[path.length() - 1] == '/') {
-    path.Add("temp_dir_");
+    path.Add(ANDROID_TEMP_DIR "/");
   }
+
+  path.Add(const_template);
   if (!path.Add("XXXXXX")) {
     // Pattern has overflowed.
     return NULL;
   }
+
   char* result;
   do {
     result = MakeTempDirectory(path.AsString());